Bowing Profile Induced by Ion Implant Damage during Silicon Gate Etching

Abstract

Precise control of gate length and shape in a dual gate scheme is a critical issue in obtaining stable and robust device performance and a high yield. The etching process for a P31-implanted silicon gate in a dual gate scheme showed a symmetrical bowing profile. The location of bowing was exactly at the projected range of ion implantation. It was confirmed that the bowing profile after the etching process arises from the implant damage, which is mostly affected by the molecular weight of the ion source and energy rather than the polarity of implant sources. However, the implant damage could be recovered by a post thermal annealing process, and then a normal silicon gate line without a bowing profile could be obtained after the gate etching.